This invention relates to an acoustic coupler and more particularly to apparatus for converting a high frequency signal available from an oscillator in an electronic watch to an audible tone which has a repetition rate indicative of those rates employed in mechanical watches.
Presently, there exists a great numer of devices which are employed in the horological industry for calibrating and testing the timing accuracy of watches and clocks. Due to the fact that a vast majority of watches are mechanical devices, these instruments are primarily adapted to test and calibrate the typical conventional mechanical timepiece.
As is well known, a mechanical timepiece provides an audible ticking which of course, relates to the accuracy or ability of the timepiece to provide an accurate indication of the time of day. The ticking as one can ascertain, is at a relatively fixed repetition rate and as indicated, is an accurate measurement of the timing instrument's ability to indicate the correct time. Hence, many existing calibration instruments employ a microphone or acoustical pickup which converts the audible ticks to an electrical signal. The watch is placed on a platform or in the vicinity of such an acoustical pickup or transducer and the ticks are then responded to.
The timing device has an internal frequency standard which is used as a reference. The timing instrument operates to compare the repetition rate of the reference with the repetition rate of the ticking. If they are in adjustment, a tape or permanent record will indicate this factor to the operator. For example, in many such instruments, if the timepiece is accurately calibrated, a tape printout will provide a straight line during the testing operation. If there is a deviation in frequency between the standard and the timepiece, the line printout will be at a positive or negative slope depending upon the nature and magnitude of the frequency drift. The operator can therefore adjust the timing mechanism until a straight line printout is achieved and hence, he can thus be assured that the timepiece is accurate within predetermined limits as depending upon the accuracy of the frequency standard included in the calibration instrument.
In any event, based on the great strides made in the field of integrated circuits and displays, there are an increasing number of watches and timepieces on the market which do not in any manner produce an audible tick. In general, such devices are designated according to the types of displays employed to provide an indication of the time of day and are referred to as LED, LCD, and so on. These devices employ a crystal oscillator which is an electronic circuit and provides an extremely accurate and stable output frequency signal.
A great majority of these watches employ such an oscillator operating at an output frequency of 32,768.00Hz or 32.768kHz. Other devices employ an oscillator with an output frequency of 786.483kHz. It is, of course, ascertained that both frequencies are not within the audible range. These frequencies are used as standards in the timing instrument and are conventionally divided to provide, for example, a one cycle per second signal which is synchronized to the oscillator frequency and therefore of the same accuracy. This signal is then counted and displayed to provide an indication of the time. The functioning and operation of such electronic devices are well known in the state of the art.
There is, of course, a problem in that the above described calibration devices which have been employed for calibrating mechanical watches cannot be used in conjunction with the above noted electronic timepieces. Hence, there are available a number of different timing instruments to be used with electronic watches. These are, in general, more expensive than the prior art mechanical calibration devices and employ different pickups and may possess, for example, both the capability of testing mechanical devices and electronic devices. Thus, such an instrument with the dual capability of calibrating both mechanical and electronic devices is more expensive than the prior art mechanical tester and requires a different discipline for use.
As indicated above, a typical mechanical device which provides a ticking will conventionally provide a ticking repetition rate of five or 10 ticks per second, as these rates are associated with reliable mechanical timing apparatus. The persons employed in the watchmaking industry are used to this repetition rate and tend to relay on the ticking to aid in calibrating the device in conjunction with the calibration instrument. Furthermore, such persons also possess a great deal of experience and knowledge gained through many years to thus enable them to reliably and effectively employ the prior art calibration instruments for such mechanical devices.
It is therefore an object of the present invention to provide apparatus for converting the crystal oscillator frequency employed in an electronic timepiece to an audible frequency having a repetition rate indicative of a mechanical timepiece to therefore enable a user to employ a prior art mechanical calibration instrument to test and calibrate electronic timepieces.